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Polydopamine + SiO2 Underlayer for Improving Diamond-like Carbon Coating Adhesion and Durability
About
This invention pertains to the use of polydopamine (PDA) and SiO2 nanoparticle composites as an underlayer for a diamond-like carbon (DLC) coating in order to reduce coating delamination and crack propagation. PDA and PDA+ SiO2 underlayers were deposited on stainless steel (SS) substrate using a digital rocking bath. Finally, a 300 nm thin DLC was fabricated on SS/PDA+ SiO2. Diamond-like carbon (DLC) coatings exhibit excellent properties such as low friction, high hardness and wear resistance, corrosion resistance, and excellent transparency at low thickness. However, DLC coatings are easily delaminated from substrates due to thermal and mechanical property mismatch between the coatings and the metallic substrates. A widely used underlayer is trimethylsilane [(CH3)3SiH], or TMS, and was used for comparison during the testing phase. This invention addresses the weak bonding between the DLC coating and substrates by using a thin adhesive underlayer with hard nanoparticles. The composite underlayer provides strong adhesion and mechanical interlocking between the DLC and the substrates. The coating significantly improved the critical loads for crack initiation and initial and global delamination compared to a commonly used DLC, thus yielded a low coating wear rate.
Key Benefits
• It has a much longer wear life than the widely used TMS/DLC. • It has a higher strength to prevent crack propagation. • It can delay initial delamination and prevent global delamination. • The wear rate is much lower compared to the TMS/DLC.
Applications
• Machine parts (any components that are designed to move in contact with another part under an applied load) • Automotive parts (engine cylinder liners, bearings, valve components, etc.) • Biomedical implants (dental implants, knee, hip joints, etc.) • Tooling components (cutting tools, end mills, drill bits, etc.) • Oil and gas pipelines